The functions of a storage apparatus (hereinafter, called “storage sub-system”) include the following functions, for example.
A first function is an automatic capacity expansion function (for example, Patent Literature 1). By means of an automatic capacity expansion function, a storage sub-system allocates a portion of the region of a physical resource (hereinafter, called a “segment”) to a logical storage area (hereinafter, called “logical volume”) in response to an access request from a host computer. By this means, the capacity of the logical volume is automatically expanded.
A second function is an access control function (for example, Patent Literature 2). By means of an access control function, a storage sub-system manages access attributes (for example, read only, writeable and readable) for each logical volume, and controls permission or denial of access to the logical volume on the basis of the access attributes corresponding to that logical volume.
A third function is a migration function (for example, Patent Literatures 3 to 5). By means of a migration function, a storage sub-system migrates the data in a logical volume to another logical volume.
A virtual logical volume of which the capacity is automatically expanded by the automatic capacity expansion function is called an “automatic capacity expansion volume” in the present specification. Furthermore, a logical storage device on a RAID (Redundant Array of Independent Disks) which is constituted by a plurality of physical storage devices (for example, hard disk drives or flash memory devices) is called a “physical resource” in the present specification. Moreover, a logical volume with which access attributes have been associated is called a “security volume”.